JP6668377B2 - Robust and lightweight piston with low compression height and method of construction - Google Patents

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is related to US Provisional Application No. 62 / 136,948 filed on March 23, 2015 and US Utility Patent Application No. 15 / 077,168 filed on March 22, 2016. And the contents of all of them are incorporated herein by reference.

BACKGROUND OF THE INVENTION TECHNICAL FIELD The present invention relates generally to internal combustion engines, and more specifically, to pistons for internal combustion engines.

2. Related Technology Engine manufacturers are facing increasing demands for improved engine efficiency and performance. Improvement demands include reducing fuel costs, reducing oil consumption, improving fuel systems, increasing compression loads and operating temperatures in cylinder bores, reducing heat loss through pistons, components, while reducing manufacturing-related costs. Including, but not limited to, improved lubrication, reduced engine weight, and further downsizing of the engine. Although it is desirable to increase the compression load and operating temperature in the combustion chamber, the trade-off is that it is still necessary to maintain the piston's structural integrity and temperature within usable limits for this purpose to be achieved. Off accompanies. Thus, these desired "increases" limit the compression height of the piston, i.e., the extent to which the overall size and mass of the piston can be reduced. This is a normal piston with an annular cooling gallery, such as a closed or substantially enclosed annular cooling gallery, which is often found necessary to keep the operating temperature of the piston within usable limits The configuration is particularly troublesome. Further, the cost of manufacturing a piston having an upper part and a lower part joined together along a joint joint to form an annular cooling gallery is less than the joint used to join the upper and lower parts together. It is generally increasing due to processes such as legalization and finishing.

  As will be apparent to those skilled in the art upon reading the disclosure herein and viewing the drawings, pistons constructed in accordance with the present invention are, inter alia, robust and lightweight, having reduced envelope and compression height, and the like. Achieve the desired benefits, while at the same time eliminating the above-mentioned and other disadvantages of the known piston arrangement.

SUMMARY OF THE INVENTION A piston constructed in accordance with the present invention is constructed as a monolithic, unitary steel, which has increased strength and durability, and has a reduced internal cylinder bore, such as compressive loads and temperatures that occur in modern high performance engines. Withstands compressive loads and increases in temperature. In addition, the novel integral construction of the piston eliminates the usual steps used to join the upper and lower parts of the piston together, lowering the costs associated with piston manufacture. Furthermore, pistons constructed in accordance with the present invention are particularly advantageous when compared to pistons having a closed or substantially closed annular cooling gallery, due to the elimination of the presence of the annular cooling gallery and the usual annular floor. Thus, the piston envelope, compression height (CH), defined as the distance extending between the pin bore axis and the upper crown combustion surface, and weight can be significantly reduced. Conventional annular floors are often used to define the lower surface of a sealed cooling gallery that extends generally parallel to the pin bore axis between opposing pin bosses. As described above, the engine in which the piston configured according to the present invention is arranged can be made smaller, lighter, and more fuel-efficient. In addition, the piston constructed in accordance with the present invention has an open crown undersurface area that extends generally between the pin bosses when looking at the bottom of the piston generally along the central longitudinal axis, due to the presence of an open crown undersurface area. Alternatively, the function of sending oil directly from the oil nozzle of the engine to the lower surface of the crown is enhanced. In addition, the piston configured according to the invention reduces the unit load between the support surface of the pin bore and the wrist pin, and between the support surface extending through the small end of the connecting rod and the wrist pin, while at the same time reducing the pin joint The ability to increase lubrication is provided. In addition, it has been shown that for pistons constructed in accordance with the present invention, the shape of the skirt has been significantly changed as desired, and the shape change of the cylinder liner has been reduced. Thus, optimal piston ring performance is provided and engine oil "blow-by" (a term known in the art as combustion gas passing through the compression ring) is suppressed. And still further, a piston constructed in accordance with the present invention cools the piston ring belt area given that a constant fresh oil supply is delivered to the open sub-crown area immediately adjacent to the ring belt area. This indicates enhanced functionality, further enhancing the ability of the piston ring to operate as intended over a long service life.

  According to one aspect of the present invention, a robust and lightweight first piston for an internal combustion engine is provided. The piston has a monolithic piston body extending along a central longitudinal axis in which the piston reciprocates within a cylinder bore of the internal combustion engine. The piston body has an upper wall defining an upper combustion surface having an annular ring belt region for fitting at least one piston ring, the annular ring belt region depending from the upper combustion surface. The piston body has a pair of skirts depending from the ring belt region for facilitating the guidance of the piston in the cylinder bore, and a wrist pin for engaging a wrist pin which is laterally aligned along the pin bore axis. And a pair of pin bosses providing a pair of pin bores, the pin bosses being joined to the skirt with struts in between. The upper combustion surface has a first portion and a second portion, the first portion extending annularly along the outer periphery of the upper wall, and the second portion hanging radially inward from the first portion. Form a bowl. The upper wall has a crown lower surface formed on the underside of the combustion bowl, diametrically opposed to the second portion of the upper combustion surface. At least a portion of the underside of the crown, defined by the skirt, struts, and pin bosses, when viewed along the central longitudinal axis, takes into account the case where the body of the piston is not perfectly round or circular. Have an open projected two-dimensional surface area that is between about 30 and 55 percent of the area defined by the maximum outer diameter. This provides a wide area where the splashed or sprayed oil can freely come into direct contact, improving cooling of the piston during use.

  According to another aspect of the present invention, the crown lower surface defined by the skirt, strut, and pin boss has a three-dimensional total greater than 30 percent of the maximum area of the piston body defined by the maximum outer diameter of the piston body. It has a surface area (surface area that traces the undulating contour of the lower surface of the crown).

  According to another aspect of the invention, there is a penetrating recess, which is diametrically opposed to one another and which is enclosed along the periphery, the penetrating recess extending to a position above the upper surface of the pin boss and below the upper wall. May be provided, the through-holes opening into the open crown underside defined by the skirt, struts, and pin bosses, further promoting cooling of the piston body and reducing the weight of the piston body.

  According to another aspect of the invention, the through recess may be non-circular when shaped in a cross-section along the axial direction, shaped to follow the immediately adjacent feature, wherein the inner wall of the through recess is adjacent The contours of the burning bowl and ring belt region that are to be traced are adapted to be traced. Therefore, it is easier to form the wall between the through-dip and the combustion bowl and between the through-dip and the ring belt region to an optimum wall thickness, so that the function of reducing the weight and the function of promoting the cooling are achieved. Is maximized.

  According to another aspect of the present invention, the through recess has an asymmetrical shape when viewed in a cross-section along the axial direction, further promoting weight reduction and cooling.

  According to another aspect of the invention, the outer edges of the skirt, strut, and pin boss extend between about 75 to 100 percent of the outer circumference of the upper combustion surface.

  According to another aspect of the present invention, a robust and lightweight second piston for an internal combustion engine is provided. The piston has a monolithic piston body extending along a central longitudinal axis in which the piston reciprocates within a cylinder bore of the internal combustion engine. The piston body has an upper wall defining an upper combustion surface having an annular ring belt region for fitting at least one piston ring, the annular ring belt region depending from the upper combustion surface. The piston body has a pair of skirts depending from the ring belt region for facilitating the guidance of the piston in the cylinder bore, and a wrist pin for engaging a wrist pin which is laterally aligned along the pin bore axis. And a pair of pin bosses providing a pair of pin bores, the pin bosses being joined to the skirt with struts in between. The upper combustion surface has a first portion and a second portion, the first portion extending annularly along the outer periphery of the upper wall, and the second portion hanging radially inward from the first portion. Form a bowl. The upper wall has a crown lower surface formed on the underside of the combustion bowl opposite the second portion of the upper combustion surface, the crown lower surface defined by the skirt, struts, and pin bosses being longitudinally lower. It is open when viewed along the central axis. The piston body further includes a penetrating recess, located diametrically opposite each other, surrounded along the periphery, the penetrating recess extending to a position above the upper surface of the pin boss and below the upper wall. Opens into the open lower surface of the crown defined by the skirt, struts, and pin bosses.

  In accordance with another aspect of the present invention, the through recess may be non-circular when shaped in a cross-section along the axial direction, shaped to follow the immediately adjacent feature.

  According to another aspect of the invention, the through recesses are asymmetric in shape when viewed in section along the axial direction.

  According to another aspect of the invention, the crown lower surface defined by the skirt, strut, and pin boss has an area defined by the largest outer diameter of the piston body when viewed along a longitudinal central axis. It has an open projected two-dimensional surface area that is between about 30-55 percent. This provides a wider area where the splashed or sprayed oil can freely contact directly and improves the cooling of the piston during use.

  According to another aspect of the present invention, the crown lower surface defined by the skirt, strut, and pin boss has a three-dimensional total greater than 30 percent of the maximum area of the piston body defined by the maximum outer diameter of the piston body. Has surface area.

  According to another aspect of the invention, the outer edges of the skirt, strut, and pin boss extend between about 75 to 100 percent of the outer circumference of the upper combustion surface.

  According to another aspect of the present invention, there is provided a method of configuring a galleryless piston of an internal combustion engine. The method includes forming the monolithic piston body using one of machining, forging, additive manufacturing (such as 3D printing), or casting, wherein the piston body includes an upper combustion surface and an upper combustion surface. An upper wall including an annular ring belt region depending from the surface. The method includes forming an upper combustion surface having a first portion and a second portion, wherein the first portion extends annularly along an outer periphery of the upper wall, and the second portion depends from the first portion. Form a combustion bowl. The method further includes forming an upper wall having a crown lower surface below the combustion bowl opposite the second portion. Further, at least a portion of the crown lower surface defined by a skirt portion, a pin boss, and struts extending between the skirt portion and the pin boss, respectively, which are located diametrically opposite each other, viewed along a longitudinal central axis. Forming at least a portion of the crown lower surface having an open projected two-dimensional surface area that is between about 30 and 55 percent of the area defined by the maximum outer diameter of the piston body. This provides a wider area where the splashed or sprayed oil can freely contact directly and improves the cooling of the piston during use.

  According to another aspect of the invention, a method is provided wherein the crown lower surface defined by the skirt, strut, and pin boss is less than 30 percent of a maximum area of the piston body defined by a maximum outer diameter of the piston body. Forming a lower crown surface having a larger total three-dimensional surface area.

  According to another aspect of the present invention, a method extends along a perimeter of a through-hole, diametrically opposed to each other, above the upper surface of the pin boss and below the upper wall. Forming a piston body having a through-going recess, the through-going opening in the open crown lower surface defined by the skirt, strut, and pin boss.

  According to another aspect of the invention, the method may include forming the through-hole using a casting method.

  According to another aspect of the present invention, the method may include casting a through recess that is non-circular when viewed in cross section.

  According to another aspect of the invention, the method may include casting a through-hole that is asymmetric in shape when viewed in cross-section.

  According to another aspect of the invention, a method may include forming an outer perimeter of a skirt, strut, and pin boss that extends between about 75 to 100 percent of the perimeter of the upper combustion surface.

  According to another aspect of the present invention, there is provided a method of configuring a galleryless piston of an internal combustion engine. The method includes forming a monolithic piston body using one of machining, forging, additive manufacturing (such as 3D printing, among other alternatives), or casting. The body has an upper wall that includes an upper combustion surface and an annular ring belt region depending from the upper combustion surface. The method includes forming an upper combustion surface having a first portion and a second portion, wherein the first portion extends annularly along an outer periphery of the upper wall, and the second portion depends from the first portion. Form a combustion bowl. The method further includes forming an upper wall having a crown lower surface below the combustion bowl opposite the second portion. Further, at least one of the open crown lower surfaces is defined by a skirt portion, a pin boss, and a strut portion extending between the skirt portion and the pin boss, respectively, which are positioned diametrically opposite each other and viewed along the longitudinal central axis. Forming a portion and a piston having a penetrating recess positioned diametrically opposite each other and extending along a peripheral edge, the penetrating recess extending above the upper surface of the pin boss and below the upper wall. Forming the body, wherein the through-hole is open on the opposite side of the pin boss and opens into the open crown underside defined by the skirt, strut, and pin boss.

  According to another aspect of the present invention, a method is provided wherein the crown lower surface defined by the skirt, strut, and pin boss is between about 30-55 percent of the area defined by the maximum outer diameter of the piston body. Forming a crown lower surface having an area of? This provides a wider area where the splashed or sprayed oil can freely contact directly and improves the cooling of the piston during use.

  According to another aspect of the invention, a method is provided wherein the crown lower surface defined by the skirt, strut, and pin boss is greater than 30 percent of a maximum area defined by a maximum outer diameter of the piston body. Forming a crown lower surface having a dimensional total surface area may be included.

  According to another aspect of the invention, a method may include forming a through-hole extending over the pin boss using a casting method.

  According to another aspect of the present invention, a method may include casting a through recess extending over a pin boss that is non-circular when viewed in cross section.

  According to another aspect of the present invention, a method may include casting a through recess extending over a pin boss that is asymmetric in shape when viewed in cross section.

  According to another aspect of the present invention, a method may include forming a peripheral edge of a skirt, strut, and pin boss that extends between about 75 to 100 percent of an outer periphery of an upper combustion surface.

  These and other aspects, features, and advantages of the present invention will be more readily understood in view of the following detailed description of the presently preferred embodiments and best mode, the appended claims, and the accompanying drawings. There will be.

FIG. 4 is a bottom view of a piston configured according to one aspect of the present invention. FIG. 2 is a cross-sectional view taken generally along line 2-2 of FIG. 1 extending generally along a central pin bore axis. FIG. 3 is a cross-sectional view generally taken along line 3-3 of FIG. 1 extending generally across the pin bore axis. FIG. 4 is a bottom view of a piston configured according to another aspect of the present invention. FIG. 5 is a cross-sectional view taken generally along line 5-5 of FIG. 4 extending generally along a central pin bore axis. FIG. 6 is a cross-sectional view taken generally along line 6-6 of FIG. 4 extending generally across the pin bore axis. FIG. 7 is a cross-sectional view generally taken along line 7-7 of FIG.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS Referring more particularly to the drawings, FIGS. 1-3 are illustrated in a cylinder bore or chamber (not shown) of an internal combustion engine, such as, for example, a modern small, high performance vehicle engine. 1 shows a view of a piston 10 configured according to a presently preferred embodiment of the present invention for reciprocating movement. The piston 10 may be a monolithic body 12 formed from and / or as a single material, such as by machining, forging, additive manufacturing (including, but not limited to, 3D printing), or casting. It is comprised so that it may have. Thereafter, if necessary, a finishing process is performed to complete the configuration. Thus, the pistons 10 are joined together, not uncommon for pistons having an enclosed or partially enclosed annular cooling gallery, defined or partially defined by the floor of a cooling gallery (cooling cavity). Does not have multiple parts joined together, such as parts and lower parts. Alternatively, the piston 10 of FIGS. 1-3 is "galleryless" and does not have any presence of a cooling gallery floor or other features that define or partially define the cooling gallery. I do not have. The piston body 12 made of steel is rugged, robust and durable to meet the high performance requirements of today's high performance internal combustion engines. That is, there is durability against an increase in temperature and compressive load. The steel used to construct the body 12 (ie, alloy steel) may be SAE grade 4140 or a different steel, depending on the requirements of the piston 10 for a particular engine application. Due in part to the fact that the piston 10 is galleryless and other features discussed below, the novel configuration of the body 12 includes, among other things discussed below, the outer envelope, weight, and Compression height (CH) is minimized. Thereby, the engine in which the plurality of pistons 10 are provided can be reduced in weight and size. Further, the novel configuration discussed and illustrated in the present specification provides sufficient piston 10 in use to withstand the harshest operating temperatures that occur in high performance engine applications, despite being galleryless. And it can be cooled optimally.

The piston body 12 has an upper head or upper portion 13 having a top wall (also referred to as an upper wall 14). The upper part 13 provides an upper combustion surface 16 which is directly exposed to the temperature limits and the combustion gas pressure in the cylinder bore of the internal combustion engine. The upper combustion surface 16 is defined by an annular first portion 18 formed as a substantially flat surface extending along the outer periphery of the upper wall 14 and a combustion bowl wall portion 21 of the upper wall 14. And two parts 20. The second portion 20 has a non-planar, undulating surface 22 extending from the planar first portion 18 and extending along the uppermost surface of the wall portion 21 of the combustion bowl. The lower crown surface 24 is formed below the wall portion 21 of the combustion bowl and directly opposite the second portion 20 of the upper combustion surface 16. Here, the crown lower surface 24 is defined as the surface of the wall portion 21 of the combustion bowl that is seen when the piston is viewed from directly below. Here, the crown lower surface 24 extends away from the second portion 20 of the upper combustion surface 16 by a spacing not exceeding twice the minimum thickness (t, FIG. 3) of the wall portion 21 of the combustion bowl. Thus, the crown lower surface 24 is generally snug to the second portion 20 of the combustion bowl 26 and provides the desired strength while minimizing the distance to the combustion bowl 26 and the undulation of the wall portion 21 of the combustion bowl. It is shaped so as to substantially trace the surface opposite to the surface 22 having the groove. The crown lower surface 24 is open when viewed from the back of the piston 10 (FIG. 1) and features an enclosed or partially enclosed cooling gallery, such as a floor, or oil or coolant near the crown lower surface 24. Are not defined by other features that tend to retain Thus, as soon as the oil comes into contact with the crown lower surface 24, it freely flows down from the crown lower surface 24 along with a fresh oil supply that maintains the cooling contact with the crown lower surface 24 while the piston 10 reciprocates in the cylinder bore.

  The annular first portion 18 of the upper wall 14 forms an outer periphery of the upper wall 14 and surrounds an annular combustion bowl 26 depending from the first portion 18, so that the combustion bowl 26 is at the top of the upper combustion surface 16. It is recessed below one part 18. The combustion bowl 26 is shown as being shaped to provide an upper apex (also referred to as a top 28). The top 28 may be coaxial on the longitudinal center axis 30 of the piston 10 with which the piston 10 reciprocates during use, or may be radially offset from the piston center axis 30 if necessary. Good. The upper portion 13 further defines a ring belt region 32 depending from the upper combustion surface 16 to provide one or more piston rings (not shown) for fitting one or more piston rings (not shown) as is common in piston configurations. A corresponding ring groove 34 is provided.

The piston body 12 further includes a lower portion 36. Lower portion 36 includes a pair of pin bosses 38 depending from upper portion 13. The pair of pin bosses 38 generally depends from the upper wall 14. Each of the pin bosses 38 has a pin bore 40, and it is preferable that there is no bearing cylinder (bush) in view of the steel configuration. Here, the pin bores 40 are coaxially spaced apart from one another along a pin bore axis 42 that extends generally across the longitudinal central axis 30. Pin boss 38 has a generally flat, radially outermost surface (referred to as outer surface 44), which is shown generally parallel to one another. The outer surfaces 44 are separated from each other by a distance PB along the pin bore axis 42 . Here, the range of the PB is as wide as possible with the new configuration of the piston body 12, and any portion of the pin boss 38 extends beyond the axial protrusion formed by the outer surface of the upper combustion surface 16. Although not intended to extend radially, the extent of the PB is rather provided to make the outermost surfaces of the outer surfaces 44 of the pin bosses 38 flush or substantially flush with each other. I have. This minimizes the surface area of the exposed area 46 extending radially outward of the outer surface 44 of the pin boss. Here, the exposed region 46 forms a lower surface portion of the ring belt region 32.

  Each of the pin bores 40 has an exposed region 46, that is, a lower surface of the ring belt region 32 and a concave uppermost support surface (hereinafter, referred to as an uppermost support surface 48) extending planarly or substantially planarly. As a result, the compression height CH is minimized (as shown in FIG. 2, the compression height is the dimension extending from the pin bore axis 42 to the upper combustion surface 16). The pin boss 38 is joined to a skirt portion (also referred to as a skirt panel 52 of the lower portion 36) located directly opposite to the outer panel (also referred to as a strut or strut portion 50). The skirt panel 52 and strut 50 define an obstruction-free open cavity 54 that extends from the bottom or bottom surface 56 of the strut 50 and skirt panel 52 to the crown lower surface 24. The open cavity 54 provides direct access to oil splashing on the crown lower surface 24 or oil sprayed directly from the interior of the crankcase onto the crown lower surface 24, thereby allowing the entire lower circumferential surface 24 to be defined. Oil from inside the crankcase can be splashed directly, and oil can be freely splashed around wrist pins (not shown). At the same time, the weight of piston 10 is significantly reduced given the lack of cooling gallery features. Thus, despite having no conventional or partially closed cooling gallery, the open configuration of the galleryless piston 10 provides excellent cooling for the crown lower surface 24 and excellent wrist pin joints in the pin bore 40. Lubrication becomes possible, and at the same time, the time during which oil stays on the surface near the combustion bowl 26 (the time during which the oil amount remains on the surface) can be reduced. This can prevent unwanted buildup of oil coke, which can occur in pistons having a closed or substantially sealed cooling gallery. In this way, the piston 10 remains "clean" over long periods of use, so that it can remain substantially free of accumulations, thereby increasing the useful life of the piston 10 and its associated components. Extend.

Increasing the spacing and distance PB between the pin bosses 38 provides excellent cooling to the crown lower surface 24 and minimizes the diameter of the wrist pin (not shown), thereby reducing the compression height CH and weight of the piston 10. Further reduce. At the same time, the unit load over the wrist pin / pin bore contact and the unit load over the wrist pin / connecting rod contact are minimized. The unit load is defined as compression load / 2D projected support surface area. When the upper support surface 48 is maximized, the unit load decreases because the distance PB increases and the width of the upper support surface 48 increases. This minimizes component stress and wear. Further, by increasing the distance between the pin bosses and the distance PB, the inner surfaces 58 of the pin bosses 38 can be further separated from each other, and the space for fitting the small end of the connecting rod increases. This increases the open area of the wrist pin extending between the inner surface 58 and the small end of the connecting rod. As described above, the function of freely splashing the oil to the exposed area of the wrist pin is improved, so that lubrication of the wrist pin joint between the pin bore 40 and the connecting rod may be increased.

It can be seen that, in addition to the above benefits, a further benefit provided by the increased spacing between pin bosses 38 is that the outer peripheral length or arc of skirt panel 52 can be increased. Unlike conventional pistons that are more rectangular, as can be seen in FIG. 1, the skirt panel 52 extends into a large arc so that the outer surface of the skirt panel 52, struts 50, and pin bosses 38 is substantially circular. I have. The skirt panel 52 is integrated with the pin boss 38 with the strut portion 50 interposed therebetween. The strut portion 50 has an arc shape and is obliquely inclined with respect to the pin bore shaft 42. This creates a smooth arcuate transition between the skirt panel 52 and the side of the pin boss 38. As the outer peripheral length (also referred to as the width) of the skirt panel 52 increases, the flexibility of the wall of the skirt panel 52 increases as compared to a stiffer and narrower skirt panel. The increased flexibility or elastic deformation of the walls of the skirt panel acts to reduce the deformation of the cylinder liner, thereby reducing the deformation of the cylinder liner and, as a result, increasing the performance of the piston ring (not shown). This reduces the amount of oil "blow-by" through the piston ring. Thus, the performance of the engine over a long service life is enhanced and improved.

  The crown lower surface 24 defined in the circumferential direction by the skirt portion 52, the strut portion 50, and the pin boss 38 has an area defined by the maximum outer diameter of the piston body 12 when viewed along the central axis 30 in the longitudinal direction. It has an open projected two-dimensional surface area that is between about 30-55 percent. This provides a wide area where the splashed or sprayed oil can freely come into direct contact, and improves the cooling of the piston 10 during use. Further, the crown lower surface 24 defined by the skirt portion 52, the strut portion 50, and the pin boss 38 is greater than 30% of the maximum area of the piston body 12 defined by the maximum outer diameter of the piston body 12, and It has a three-dimensional total surface area that is approximately between 30 and 90 percent of the maximum area defined by the outer diameter. The maximum outer diameter of the piston body 12 is usually determined by the diameter of the uppermost region of the piston 10.

  4-7, a piston 110 configured according to another aspect of the present invention is shown, wherein the same reference numerals plus 100 are used to provide similar features in FIGS. Has been identified. Those skilled in the art will readily recognize features similar to those not identified by a reference number, but described and identified using the above reference numbers. Piston 110 has substantially the same features as described for piston 10. In addition to this, there are penetrating depressions (hereinafter, referred to as depressions 60) which are located diametrically opposite each other and are surrounded along the periphery (outer periphery). Recess 60 extends above upper surface 62 of pin boss 138 and directly below upper wall 114. Here, recess 60 has opposing ends that open into an open galleryless area of crown lower surface 124 defined by skirt panel 152, strut 150, and pin boss 138. Thus, except for the recesses 60 diametrically opposite each other, which are enclosed along the perimeter, the piston 110 is galleryless and therefore has no enclosed or partially enclosed chambers or regions. Thus, when viewed along the central longitudinal axis 130 of the piston 110, it should be seen that the piston 110 is completely open and exposed.

  A circumferentially recessed recess 60 extends immediately adjacent the upper combustion surface 116 located between and radially aligned with the combustion bowl 126 and the ring belt region 132. The indentation 60 extends immediately adjacent to and is partially defined by both the lower portion of the combustion bowl 126 and the ring belt region 132, and is defined by the overall length or substantially the axial length of the ring belt region 132. Is spread over the entire length. Thus, the combustion bowl rim, a portion of the upper combustion surface 116 that is axially aligned with the enclosed indentation 60, the area of the combustion bowl 126 located opposite the indentation 60 across the top wall 114, and Cooling of the portion of the ring belt region 132 extending beyond the pin bosses 138 between the skirt panels 152 as well as regions such as the piston ring is facilitated by the indentation 60, thereby improving the performance of the piston ring, and It also helps transfer heat from the piston 110 to the cylinder liner. The hollow, circumferentially enclosed recess 60 provides the additional benefit of a significant reduction in the weight of the piston 110. At the same time, high durability of the piston 110 is maintained by the peripheral wall defining the enclosed recess 60.

  The outer peripheral inner wall surface 64 that defines the indentation 60 can have any desired profile, such that the profile of the immediately adjacent feature, such as the combustion bowl 126, the ring belt region 132, and the pin bore 140, can be traced. Thus, the inner wall surface 64 of the recess 60 may be non-circular, asymmetric, or any other shape desired when viewed in an axial cross-section, such that the recess 60, the combustion bowl 126, and the ring belt By reducing the thickness of the wall material between the region 132, cooling and weight reduction are facilitated. This is facilitated by additive manufacturing printing or by casting the piston 110, such as by lost material casting, investment casting, or another method. The casting process is facilitated by providing the open injection area 66 of the recess 60 with direct and free access through the galleryless area of the adjacent crown lower surface 124.

  The crown lower surface 124, which is defined circumferentially by the skirt 152, the strut 150, and the pin boss 138, when viewed along the longitudinal central axis 130, has an area approximately equal to the area defined by the maximum outer diameter of the piston body. It has an open projected two-dimensional surface area that is between 30 and 55 percent. This provides a wide area where the splashed or sprayed oil can freely come into direct contact, and improves the cooling of the piston 110 during use. In addition, the crown lower surface 124 defined by the skirt 152, the strut 150, and the pin boss 138 is greater than 30 percent of the maximum area of the piston body defined by the maximum outer diameter of the piston body, and the maximum outer diameter of the piston body Has a three-dimensional total surface area that is approximately between 30 and 90 percent of the maximum area defined by に よ っ て. The maximum outer diameter of the piston body is usually determined by the diameter of the uppermost region of the piston 110.

  Many modifications and variations of the present invention are possible in light of the above teachings. Thus, it is to be understood that the invention may be embodied in other forms than specifically described, and the scope of the invention is defined by the appended claims.

Claims (27)

A piston of an internal combustion engine,
An upper combustion surface comprising a monolithic piston body extending along a central longitudinal axis in which the piston reciprocates within a cylinder bore, the piston body having an annular ring belt region for fitting at least one piston ring. Wherein the annular ring belt region depends from the upper combustion surface, the upper combustion surface having a first portion and a second portion, wherein the first portion comprises Extending annularly along the outer periphery of the upper wall, the second portion defines a combustion bowl depending radially inward from the first portion, and the upper wall is positioned directly opposite the second portion. Having a crown lower surface formed below the combustion bowl,
The piston further comprises:
A pair of skirts depending from the ring belt region to facilitate guiding the piston in the cylinder bore;
A pair of pin bosses that provide a pair of pin bores for fitting wrist pins that are laterally spaced and aligned along a pin bore axis, the pin bosses being joined to the skirt with struts in between;
The lower crown surface is defined by the skirt portion, the strut portion, and the pin boss, and has an area of about 30 of an area defined by the maximum outer diameter of the piston body when viewed along the longitudinal center axis. A piston having an open projected 2D surface area that is between -55 percent area.   The crown lower surface defined by the skirt, the struts, and the pin boss, has a three-dimensional total surface area greater than 30 percent of the area defined by a maximum outer diameter of the piston body. The described piston.   The piston body has dents diametrically opposite each other and surrounded along a periphery, the recesses extending to a position above an upper surface of the pin boss and below the upper wall. 2. The piston according to 1.   4. The piston of claim 3, wherein the enclosed recess is non-circular when viewed in a cross-section along the axial direction.   5. The piston of claim 4, wherein the enclosed recess is asymmetrical when viewed along an axial cross section.   The piston of claim 1, wherein an outer peripheral edge of the skirt, strut, and pin boss extends between about 75 to 100 percent of an outer periphery of the upper combustion surface. A piston of an internal combustion engine,
An upper combustion surface comprising a monolithic piston body extending along a central longitudinal axis in which the piston reciprocates within a cylinder bore, the piston body having an annular ring belt region for fitting at least one piston ring. Wherein the annular ring belt region depends from the upper combustion surface, the upper combustion surface having a first portion and a second portion, wherein the first portion comprises the upper portion. The second portion extends annularly around the perimeter of the wall, the second portion forming a combustion bowl depending radially inward from the first portion, and the upper wall is diametrically opposed to the second portion. A crown lower surface formed on a lower side of the combustion bowl;
The piston further comprises:
A pair of skirts depending from the ring belt region to facilitate guiding the piston in the cylinder bore;
A pair of pin bosses that provide a pair of pin bores for fitting wrist pins that are laterally spaced and aligned along a pin bore axis, the pin bosses being joined to the skirt with struts in between;
The crown lower surface is defined by the skirt portion, the strut portion, and the pin boss, and has an open projected two-dimensional surface area when viewed along the longitudinal central axis;
The pin boss has a pin boss outer surface facing outward in the direction of the pin bore axis,
Said piston body, diametrically opposite one another, comprising a depression through enclosed along the periphery, have a recess through which extends to a position which is below the upper in and the top wall of the upper surface of the pin boss The penetrating recess extends radially outside the outer surface of the pin boss, the penetrating recess opening into the open lower surface of the crown defined by the skirt, the strut, and the pin boss. A piston. 8. The piston of claim 7, wherein the enclosed through recess is non-circular when viewed in a cross-section along the axial direction.   The piston of claim 7, wherein the open projected two-dimensional surface area is between about 30 and 55 percent of an area defined by a maximum outer diameter of the piston body.   The crown lower surface defined by the skirt, the struts, and the pin boss has a three-dimensional total surface area greater than 30 percent of the area defined by a maximum outer diameter of the piston body. The described piston.   The piston of claim 7, wherein the outer edges of the skirt, strut, and pin boss extend between about 75 to 100 percent of an outer circumference of the upper combustion surface. A method of configuring a piston of an internal combustion engine,
Forming a monolithic piston body having an upper wall including an upper combustion surface and an annular ring belt region depending from the upper combustion surface; and forming the upper combustion surface having a first portion and a second portion. Wherein the first portion extends annularly along an outer periphery of the upper wall, the second portion forms a combustion bowl depending radially inward from the first portion, the method comprising: And a skirt portion, a pin boss, and a strut portion extending between the skirt portion and the pin boss, which are respectively diametrically opposed to each other, and a crown lower surface defined at least in part by diametrically opposite to the second portion. Forming below the combustion bowl and defined by the maximum outer diameter of the piston body when viewed along a longitudinal central axis. An area of between about 30 to 55 percent of the area, including the step of forming the defined crowns lower surface having an open projected two-dimensional surface area, methods.   13. The method of claim 12, further comprising forming the crown lower surface defined by the skirt, the struts, and the pin bosses having a three-dimensional total surface area greater than 30 percent of the area of the piston body. Method.   Forming the piston body having circumferentially enclosed recesses diametrically opposite each other, the recesses extending to a position above the pin boss upper surface and below the upper wall. 13. The method of claim 12, further comprising, wherein the indentation opens into the open lower surface of the crown defined by the skirt, the strut, and the pin boss.   The method of claim 14, further comprising forming the enclosed recess using a casting method.   The method of claim 15, further comprising casting the enclosed cavity that is non-circular when viewed in cross section.   17. The method of claim 16, further comprising the step of casting the enclosed recess, which is asymmetric when viewed in cross section.   13. The method of claim 12, further comprising forming an outer perimeter of the skirt, strut, and pin boss extending between about 75-100 percent of an outer periphery of the upper combustion surface.   13. The method of claim 12, further comprising forming the piston using one of machining, forging, additive manufacturing, 3D printing, or casting. A method of configuring a piston of an internal combustion engine,
Forming a monolithic piston body having an upper wall including an upper combustion surface and an annular ring belt region depending from the upper combustion surface; and forming the upper combustion surface having a first portion and a second portion. Wherein the first portion extends annularly along an outer periphery of the upper wall, the second portion forms a combustion bowl depending radially inward from the first portion, the method comprising: And a skirt portion, a pin boss, and a strut portion extending between the skirt portion and the pin boss, which are respectively diametrically opposed to each other, and a crown lower surface defined at least in part by diametrically opposite to the second portion. Forming below the combustion bowl; and defining the defined crown having an open surface area when viewed along a longitudinal central axis. Forming a lower surface and forming recesses diametrically opposite each other and extending along the periphery, the recesses extending above the upper surface of the pin boss and below the upper wall; And wherein the pin boss has a pin boss outer surface facing outwardly in the direction of a pin bore axis, wherein the enclosed recess extends radially outside of the pin boss outer surface, the enclosed recess being Opening into the open lower surface of the crown defined by the skirt portion, the strut portion, and the pin boss .   21. The method of claim 20, further comprising forming the enclosed recess using a casting method.   22. The method of claim 21, further comprising casting the enclosed recess that is non-circular when viewed in cross section.   23. The method of claim 22, further comprising the step of casting the enclosed cavity that is asymmetric when viewed in cross section.   21. The method of claim 20, further comprising forming the defined crown lower surface having a three-dimensional total surface area greater than 30 percent of the area of the piston body. An area of between about 30 to 55 percent of the area defined by the maximum outer diameter of the piston body, having an open projected two-dimensional surface area, further comprising the step of forming said crown underside which is image constant, wherein Item 21. The method according to Item 20,   21. The method of claim 20, further comprising forming an outer peripheral edge of the skirt, the strut, and the pin boss extending between about 75-100 percent of an outer periphery of the upper combustion surface.   21. The method of claim 20, further comprising forming the piston using one of machining, forging, additive manufacturing, 3D printing, or casting.

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